I installed Autodesk BDS 2014 on my Windows 7 64-bit computer yesterday. Today, I noticed my ribbon in Revit Architecture 2012 was not working correctly. The first step is to verify all updates or service packs are installed for your specific program. If they are, the following should help you resolve the Ribbon problem.
The problem is between Revit and .NET 4.5. The fix or work-around is to uninstall .NET 4.5 and replace with .NET 4.0. Ribbons now appear to work correctly. However, you should verify .NET 4.5 is not required by other programs.